The invention relates to the automated manufacturing of a three-dimensional object whose design has been created with a computer aided design (CAD) machine, and, in particular to such manufacture with reduced warpage and dimensional distortion in the object shape.
Modern day manufacturing has created a considerable need for flexibility in the manufacturing process. Several systems and methods for manufacturing three-dimensional objects, which have been designed on a computer, have been proposed. However, turning a computer aided design into a solid three-dimensional object quickly and inexpensively remains a problem to which considerable attention need be given.
Technology, commonly referred to as direct cad manufacturing (DCM), has been rapidly developing. In desk top manufacturing, a three-dimensional object is created on a computer screen using a CAD program. Any physical product that is designed, shaped, or prototyped prior to production could benefit from DCM. Industries that may use DCM include automotive, aerospace, appliance, toy manufacturers, and any process that involves the design, redesign, prototyping, and production of three-dimensional models, molds, patterns, or short production runs. Designs that once required weeks or months to be turned into actual models or prototypes can become objects in a matter of hours or days using DCM. Using DCM, a design can be recalled from a library and the object manufactured in just a short period of time, thus eliminating the need for large inventories. Basically, there are five identifiable desk top manufacturing systems and methods.
First is ballistics particle manufacturing as disclosed in U.S. Pat. No. 4,665,492. In this system, the coordinates of a three-dimensional design are stored in a computer data base. Particles are directed to specific locations and built up and deposited to construct the desired object. Second, in photochemical machining, shapes are formed by the polymerization of a monomer, or by sculpting a solid block of plastic, for example, see U.S. Pat. Nos. 4,078,229; 4,238,840; and 4,571,377. In polymerization, one laser may pump a photo initiator or photosynthesizer, while a second laser pumps energy. Polymerization takes place where the two beams intersect. When using the other sculpting technique, a block of rigid plastic is carved by degrading material at the intersection of the two beams. Third is laminated object manufacturing where objects are constructed by the successive deposition of thin layers of powdered plastics or metals, thin layers of powder are deposited, then compressed with a heated press platform or by roller compression. Pulses from a single laser then sinter or melt the powder in the desired cross-sectional shape and to the required depth. An example of this type system can be seen in U.S. Pat. No. 4,752,352. Fourth is selective laser sintering where objects may be fabricated by the successive deposition and sintering of thin layers of powdered material, either plastic or metal. The powder layers are spread by a feeding mechanism, but are not compressed. Sintering energy can come from a laser or other suitable direct beam of energy. Fifth, stereolithography is a form of stereolithographic printing wherein a single laser beam cures successive thin layers of liquid monomer by a series of controlled photopolymerization reactions such as shown in U.S. Pat. No. 4,575,330.
Further, U.S. Pat. No. 4,749,347 discloses a topology fabrication apparatus in which a three-dimensional solid body having a predetermined topography is automatically manufactured using an extrusion process. Thin sections of the solid body are extruded and successively built up next to each other to form the topographical form such as a topology model made from topographical map information. This system requires a fairly sophisticated apparatus and control for forming what is a relatively simple form. The types of objects which can be made with such an apparatus and control are relatively limited.
In some of the above methods and systems, the ability to form an accurate object is limited by the mechanical system employed. For example, as an object is formed and cured, there may be some shrinkage or warpage which cause the object to warp, depending on the method or system employed. In the field of desk top manufacturing or computer aided manufacturing, the formation of an accurate object without inherent warpage, or other distortion, is a problem to which considerable attention need to be given.
Accordingly, an important object of the present invention is to provide a method and system for the computer aided manufacture of three-dimensional objects in which warpage or other distortion of the object is reduced.
Another object of the present invention is to provide a system and method for automatically manufacturing three-dimensional objects whose design has been created on a CAD machine in which the object is mechanically supported during the manufacturing process to reduce warpage, or other distortion of the object during formation.